To define more clearly and to treat those disorders affecting the neuromuscular apparatus which present primarily with episodic weakness or paralysis or are characterized by a significant amount of myotonia, i.e., conditions in which the main site of intermittent dysfunction is somewhere within the muscle fiber plasma-lemma, T-system, sarcoplasmic reticulum, or myofibrillar complex --i.e., the total excitation-contraction coupling mechanism. With respect to periodic paralysis syndromes, studies are done with agents which are transiently either therapeutic or provocative, with a view of obtaining more information regarding abnormalities of pertinent metabolic pathways and methods of treatment. The various myotonia disorders are studied with respect to more clearly defining the molecular abnormalities, seeking the underlying pathogeneses and treatment thereof, and finding better ways of symptomatically treating their myotonia. Induced animal-models of myotonia are also used for these purposes. Tissue culture of the human abnormal muscle is used to reincarnate the disease in culture and thence its analysis, e.g., with microelectrodes, and its treatment; cultured human or animal muscle is also used for induction of models of diseases in vitro by chemical agents.